ESSENTIAL NEUROLOGY - PART 10 pps

Management of infections of the nervous system Prophylaxis It is not trite to emphasize the importance of the preventive measures which are current in the UK to control CNS infections. We must not become lulled into complacency or lack vigilance over such matters. • Comprehensive immunization of the population in the case of polio, tetanus and tuberculosis. • Encouragement of immunization against measles, mumps and rubella. • Measures to prevent the spread of rabies and AIDS. •Proper care of patients with compound skull fractures, CSF rhinorrhoea and otorrhoea, otitis media, frontal sinusitis and orbital cellulitis. • Early active treatment of any infection in diabetic or immunocompromised patients. Diagnosis Some infections will be identified from their clinical features alone, e.g. herpes zoster. In the case of acute meningo-encephalitis, the ideal way to es- tablish the diagnosis is urgent CT scan (to exclude a cerebral abscess mass lesion), followed by immediate lumbar puncture. Blood culture and other investigations are important, but it is the CSF which is usually most helpful in diagnosis, as shown in Fig. 15.6. In patients with a suspected cerebral abscess, urgent CT brain scan is the investigation of choice, followed by bacteriological diagnosis of pus removed at neurosurgery. Treatment Appropriate oral and intravenous antibiotic administration, always in consultation with the microbiology laboratory, constitutes the main line of treatment for pyogenic bacterial, tuberculous, fungal and protozoal infections. Topical and systemic administration of the antiviral agent aciclovir is used in herpes simplex and zoster infections. Ganciclovir is active against CMV infections. There is now a wide range of drugs active against HIV, and it has been shown that combinations of these drugs are very useful in reducing viral load, maintaining the effectiveness of the immune system and preventing the complications of AIDS. This approach is referred to as HAART (highly active anti-retroviral therapy). General supportive measures for patients whose conscious 250 CHAPTER 15 •Prevent • Diagnose •Treat • Ask why ENN15 12/2/04 4:36 PM Page 250 INFECTIONS OF THE NERVOUS SYSTEM 251 level is depressed are often required of medical, nursing and physiotherapy staff (see Fig. 11.7, p. 187). Reason for the infection In every patient with a CNS infection, the question must be asked ‘Why has this infection occurred in this patient?’. Such a question will detect imperfections of immunization, the pres- ence of diabetes, a state of impaired immunity, a previously un- detected site of access or source for infection, a personal contact accounting for the infection, or a visit to a part of the world where the infection is endemic. Such an enquiry is an essential part of the patient’s management. Pyogenic bacterial meningitis Viral meningitis or meningo- encephalitis Tuberculous meningitis Fungal meningitis Cerebral abscess Polymorph count N or Lumbar puncture should not be performed, it is potentially dangerous N Lymphocyte count Protein conc. Glucose conc. Microscopy and culture Viral antibodies in blood and CSF N or N or N or Fig. 15.6 CSF abnormalities in various CNS infections. ENN15 12/2/04 4:36 PM Page 251 Post-infective neurological syndromes Figure 15.7 shows this group of rare conditions involving the central or peripheral nervous system soon after an infection; Guillain–Barré syndrome is probably the most common. 252 CHAPTER 15 Nature of prior infection Many and varied Many and varied Influenza, varicella and other viruses Group A streptococci Target structure in the nervous system Myelin around blood vessels in the central nervous system Myelin in nerve roots, cranial nerves and peripheral nerves Mitochondria in brain and liver Basal ganglia Syndrome Acute disseminated encephalomyelitis Guillain–Barré syndrome Reye's syndrome Sydenham's chorea Tourette syndrome Post-encephalitic parkinsonism Fig. 15.7 Post-infective neurological syndromes. Acute disseminated encephalomyelitis Days or weeks after an infection or immunization, a multifocal perivascular allergic reaction in the CNS, associated with perivascular demyelination, may occur. The clinical expression of such an occurrence varies from mild features of an acute encephalomyelitis, to more major focal or multifocal neurological deficits, to a life-threatening or fatal syndrome with epileptic seizures, major bilateral neurological signs, ataxia, brainstem signs and coma. Guillain–Barré syndrome In this condition (fully described in Chapter 10, see p. 163), the post-infectious immunological lesion affects the spinal nerve roots, and the cranial and peripheral nerves. There is damage to the myelin. After a phase of damage, which may show itself by progressive weakness and numbness over 1–4 weeks, the clini- cal state and pathological process stabilize, with subsequent gradual recovery. Recovery from Guillain–Barré syndrome is usually complete, whereas persistent deficits are not uncommon after severe acute disseminated encephalomyelitis. Schwann cells can reconsti- tute peripheral nerve and nerve root myelin with much greater efficiency than oligodendrocytes can repair myelin within the CNS. ENN15 12/2/04 4:36 PM Page 252 Reye’s syndrome In this condition, which occurs in young children, there is dam- age to the brain and liver in the wake of a viral infection (espe- cially influenza and varicella). Treatment of the child’s infection with aspirin seems to increase the chances of developing Reye’s syndrome (so avoidance of the use of aspirin in young children has been recommended). Vomiting is a common early persistent symptom, rapidly progressing to coma, seizures, bilateral neurological signs and evidence of raised intracranial pressure due to cerebral oedema. The primary insult seems to involve mitochondrial function in both the brain and liver. Abnormal liver function is evident on investigation, with hypoglycaemia, which may clearly aggra- vate the brain lesion. Post-streptococcal syndromes The classic neurological sequel of Group A steptococcal sore throat is subacute chorea, sometimes accompanied by behav- ioural disturbance, termed Sydenham’s chorea or St Vitus’ dance. It is usually self-limiting, subsiding after a few weeks. It is now rare in the UK but remains common in some parts of the world such as South Africa (see p. 75). A different post-streptococcal syndrome is now seen more often in the UK, where the movement disorder is dominated by tics or sometimes parkinsonism, and does not always remit. Such cases can be indistinguishable from Gilles de la Tourette syndrome and post-encephalitic parkinsonism (encephalitis lethargica) respectively, and it is possible that an autoimmune response to streptococcus lies behind these conditions (see p. 76). In all these conditions, positive streptococcal serology (raised antistreptolysin O or anti-DNAse B titres) points towards the diagnosis. INFECTIONS OF THE NERVOUS SYSTEM 253 ENN15 12/2/04 4:36 PM Page 253 254 CHAPTER 15 CASE HISTORIES Case 1 A 63-year-old warehouse worker with a past history of bronchiectasis is admitted as an emergency after a series of epileptic seizures which begin with jerking of the left leg.He is unrousable but his wife says that over the last 4 days he has complained of severe headache and has become increasingly drowsy and apathetic. On examination he has a temperature of 37.8°C but no neck stiffness.He does not open his eyes to pain but groans incoherently and attempts to localize the stimulus with his right hand.The left-sided limbs remain motionless and are flaccid and areflexic.His left plantar response is extensor. He does not have papilloedema.General examination is unremarkable apart from crackles in his right lower chest. a. How would you manage his case? Case 2 A 18-year-old student spends a month in Thailand on her way back from a gap year in Australia. On returning to the family home she feels lethargic and irritable.She sleeps badly,has no appetite and is losing weight.After 2 weeks she begins to experience continuous dull headaches;she is referred to hospital after a further 2 weeks when she begins to vomit. She is drowsy but orientated with a normal Glasgow coma score.She looks unwell and has low- grade fever and neck stiffness with no focal neurological deficit.She has a mild neurophilia and a markedly raised CRP.Other routine blood tests,and films looking for malarial parasites,are normal. Her CT brain scan shows no definite abnormality,although there is a suggestion of abnormal enhancement of the meninges around the base of the brain.At lumbar puncture her CSF contains 20 polymorphs and 80 lymphoctytes (normally less than 4),a protein of 1.8g/ dl (normally less than 0.5) and a glucose of 2.2mmol/l at a time when her blood glucose is 6.6mmol/l (when normal CSF glucose is at least 50% of the blood level). a. What is the diagnosis? (For answers,see pp.267–8.) ENN15 12/2/04 4:36 PM Page 254 Chapter 2 Case 1 a. • CT brain scan, which in this instance showed no definite abnormality, just a suggestion of subarachnoid blood. • Lumbar puncture produced unequivocal, uniformly bloodstained CSF. b. • Neurosurgical referral. • Cerebral angiography, which demonstrated a single pos- terior communicating artery aneurysm on the left. The patient was started on nimodipine and proceeded to sur- gery without delay. A clip was placed around the neck of the aneurysm. The post-operative period was complicated by a transient right hemiparesis, which recovered completely after 10 days. The patient’s BP settled to 120/80. She has had no fur- ther problems. Case 2 a. Right-sided intracerebral haemorrhage. b. Right-sided intracerebral haemorrhage. c. CT brain scan, which shows a large clot of blood centred on the right internal capsule. ECG and chest X-ray both confirm left ventricular hypertrophy. d. He needs to know that his wife is in a grave situation, with regard to both survival (comatose, obese lady in bed) and useful neurological recovery. All appropriate care was given to this woman, but she devel- oped a deep vein thrombosis in her left calf on day 2, and died suddenly from a pulmonary embolus on day 4. Answers to case histories 255 ENNAN 12/2/04 4:40 PM Page 255 Chapter 3 Case 1 a. She has signs of a lesion in the left cerebellopontine angle, with ataxia, loss of the corneal reflex (cranial nerve 5) and deafness (cranial nerve 8). It has come on slowly, starting with deafness, so it is more likely to be an acoustic neuroma than a metastasis from her previous cancer. An MR scan confirmed this. The neuroma was too large to treat with radiotherapy but was successfully removed, giving her a transient left facial weakness (cranial nerve 7) and permanent complete left deafness. Case 2 a. It is hard to localize his symptoms to a single part of the brain. There are problems with memory (temporal lobes), behaviour and expressive language (frontal lobes) and spatial ability (parietal lobes). This could indicate a multi- focal process such as metastases, a widespread diffuse process such as a glioma, or just possibly a focal tumour with hydrocephalus. The drowsiness and papilloedema indicate raised intra- cranial pressure, making a degenerative disease or meta- bolic encephalopathy unlikely. There are pointers towards an underlying systemic disease in the weight loss and lym- phadenopathy. His CT brain scan showed widespread multifocal areas of high-density tissue in the white matter around the lateral ventricles. The appearances were typical of a primary CNS lymphoma. His HIV test was positive and his CD4 lympho- cyte count was very low, indicating that the underlying disorder was AIDS. He continued to deteriorate despite steroids and highly active anti-retroviral therapy, and died 4 weeks later. The diagnosis of lymphoma was confirmed by autopsy. Areas with a very high HIV prevalence, such as sub- Saharan Africa, are seeing a huge and increasing burden of neurological disease due to AIDS. Chapter 4 Case 1 a. Your initial management plan would comprise: • admission to hospital; • half-hourly neurological observations recorded on a 256 ANSWERS TO CASE HISTORIES ENNAN 12/2/04 4:40 PM Page 256 Glasgow Coma Scale chart by competent staff, regardless of the boy’s location, e.g. A& E, ward, CT scanner etc.; •urgent CT brain scan. b. When he starts to deteriorate, you should obtain immediate neurosurgical advice and follow it. The clinical situation strongly suggested a left-sided extradural haematoma which was confirmed by the CT scan and immedi- ately drained in an emergency operation. Thankfully the boy made a full recovery from a potentially life-threatening situation. Case 2 a. The point here is that you cannot simply assume that his coma is due to alcohol intoxication. People who abuse alcohol are very prone to head injury either through accidents or assaults. If they have a long-standing problem their clot- ting may be defective because of liver disease, increasing the risk of subdural, extradural and intracranial haemorrhage. They have an increased risk of epileptic seizures when in- toxicated, when withdrawing from alcohol and as a con- sequence of previous head injuries, and he could be in a post-epileptic coma. Aseizure can cause a head injury. Alcohol abuse increases blood pressure and the risk of stroke. People with alcohol problems often neglect their health: he could be in a diabetic coma. He may be depressed and have taken an overdose. He might even have contracted meningitis in the back bar. Do not jump to conclusions when assessing an intoxicated patient. Chapter 5 Case 1 a. She has clearly got parkinsonism, with gait disturbance, bradykinesia and rigidity. Parkinson’s disease is quite com- mon at this age, but is not usually symmetrical like this. There are no additional neurological features to suggest a more complex neurodegenerative disease. The vital part of the history is to establish what pills she is taking. The treatment for her gastro-oesophageal reflux turned out to be the dopamine antagonist metoclopramide. This was stopped and her drug-induced parkinsonism slowly resolved, although it was a year before she felt back to normal. ANSWERS TO CASE HISTORIES 257 ENNAN 12/2/04 4:40 PM Page 257 Case 2 a. This is a very difficult case. The main problem is cerebellar ataxia, with ataxia of gait accompanied by milder limb ataxia and cerebellar dysarthria. But the disease process is affecting several other systems: his optic nerves, causing optic atrophy; his spinal cord, giving extensor plantars; and his peripheral nerves, causing areflexia and impaired distal vibration sense. b. This is a condition called Friedreich’s ataxia. It is a reces- sively inherited, early-onset form of multisystem degenera- tion that is classified under the term ‘spinocerebellar ataxia’. It is due to a trinucleotide expansion in the frataxin gene, which is believed to have a role in the function of mitochon- dria. It goes on to affect other systems of the body, causing cardiomyopathy or diabetes mellitus. It is very rare, except in clinical exams. You may have considered the possibility of multiple scle- rosis, which is a much commoner cause of cerebellar ataxia, optic atrophy and extensor plantars, but rare at this age, not usually gradually progressive and not affecting the periph- eral nerves like this. If he was much older you would con- sider alcohol toxicity. This is a common cause of ataxia and peripheral neuropathy, but would not readily explain the optic atrophy or extensor plantars. c. Clearly there are going to be a great many difficult matters to discuss with the patient and his family as they face the prospect of a progressive, disabling degenerative disease in early adult life. But there may be particular issues for the par- ents in relation to the genetics. Firstly, they may feel irra- tionally guilty that they have unknowingly each carried a genetic mutation that has contributed to their son’s illness. Secondly, they will have worries about his younger siblings, who each have a 25% risk of inheriting the illness too. The help of specialists in medical genetics is likely to be invalu- able in helping them to approach these issues. Chapter 6 Case 1 a. You should probably start by examining the patient your- self, but it is perfectly legitimate to say that if you are in doubt you should get advice from a more experienced colleague too. The patient has a pattern of weakness that is typical of upper motor neurone weakness in the lower limbs, where the extensor muscles remain relatively strong and the hip 258 ANSWERS TO CASE HISTORIES ENNAN 12/2/04 4:40 PM Page 258 flexors, knee flexors and ankle dorsiflexors become weak. The extensor plantar responses also indicate an upper motor neurone problem. It often takes a few days before the reflex- es become brisk when upper motor neurone weakness comes on acutely, so you should not worry that the reflexes are still normal here. In other words, the problem is somewhere in the spinal cord. It is unlikely to be in the neck because the arms are not affected. You need an MR of the thoracic region, not the lumbosacral region, because the cord ends adjacent to the L1 vertebral body (Fig. 6.1). The sensory signs may be very helpful in this situation. The patient felt pin-prick as blunt in his lower abdomen below his umbilicus and throughout both lower limbs. This is a T9 sensory level, indicating that the cord problem is at or above this dermatome. You call the radiologist back and ask for the appropriate scan. This shows a metastasis com- pressing the cord in the mid-thoracic region. His pain and neurological deficit improve with high-dose steroids and radiotherapy. Further investigation reveals several other bone metastases from prostate cancer. This is treated med- ically, with a useful period of palliation. Case 2 a. The sensory symptoms on neck flexion (so-called L’Her- mitte’s symptom) help to localize the problem to the neck. Urgency of micturition is also a helpful indicator of a prob- lem in the spinal cord. The signs are more specific, indicating pathology at the level of the 5th and 6th cervical vertebrae. He has the seg- mental sign of absent C5–6 biceps and supinator jerks, and tract signs below this level: brisk C7–8 triceps jerks and upper motor neurone signs in the lower limbs. b. The most common pathology at this location in someone of this age is cervical spondylosis, with a C5–6 disc bulge and osteophyte formation compressing the cord. This turned out to be the cause here. There are several other rarer pos- sibilities, including a neurofibroma. Because of his delicate manual occupation, he was keen to have decompressive surgery. This stopped his electric shocks and improved the sensation in his hands. The signs in his legs remained unchanged. His bladder symptoms persisted but responded to anticholinergic drugs. ANSWERS TO CASE HISTORIES 259 ENNAN 12/2/04 4:40 PM Page 259 [...]... epilepsy 197 intervertebral disc disease 143 multiple sclerosis 106 paraplegia 93 spinal extradural abscess 241 multifocal neuropathy 146, 162 multi-infarct dementia 31 multiple sclerosis 22, 79, 99 aetiology 107 case history 109 , 260 clinical expression 103 –5, 113, 128 and dementia 232 diagnosis 106 lesions 100 –1 dissemination 102 management 107 –8 paraplegia in 90, 91, 94 tremor in 68 multiple system... pons demyelination 104 lesions 10, 37, 78 position sense 6 loss of 9, 17, 18, 80 post-concussion syndrome 63, 220 posterior cerebral arteries 26 ischaemia 29 occlusion 113, 114 posterior column 84 posterior dysphasia 227 posterior fossa 40 tumour 79 posterior interosseous nerve palsy 147 posterior tibial nerve palsy 148 post-herpetic neuralgia 143, 220 post-infective syndromes 252–3 post-streptococcal... tumour 145 panhypopituitarism 48 panic attacks 203 papillitis 103 papilloedema 187 in intracranial haemorrhage 33, 34, 35 in raised intracranial pressure 45, 113 paradoxical embolism 28 paralysis 3 paraparesis 10 paraphasias 227 paraplegia 83–98 in multiple sclerosis 105 , 108 Parinaud’s syndrome 116 parkinsonism 69, 73 case history 82, 257 post-encephalitic 253 275 Parkinson’s disease 22, 67, 69–70 dysarthria... junction 3 lesions 13 neuropathy see peripheral neuropathy neurosyphilis 233, 248 nigrostriatal pathway 69, 71, 73 nimodipine 36 non-bacterial endocarditis 28 non-fluent dysphasia 227 non-steroidal anti-inflammatory drugs in icepick headache 216 nystagmus 16, 79 in multiple sclerosis 104 rotatory 81 INDEX obsessive–compulsive disorder in Gilles de la Tourette syndrome 76 obturator nerve palsy 148 occupation... 264 spastic paraparesis 96 speech 133 speech therapy, after stroke 30 sphincter function, loss of 10 spinal accessory nerve 129 spinal cord anatomy 83–5 demyelination 104 –5 disease 18, 81 lesions cervical 10 indications of level 10, 86 segmental signs 88–9 tract signs 86–7, 89 upper motor neurone signs 10 subacute combined degeneration 93 spinal extradural abscess 93, 241 spinal nerve 138, 139 spine... viral 243 meningococcal infection 244 meningo-encephalitis, acute 242–4 meralgia paraesthetica 153 mesial temporal sclerosis 199 metastatic tumour brain 49, 51, 53 spine 98, 144, 258–9 methanol poisoning 113 methysergide 216 metoclopramide movement disorder induced by 75 parkinsonism induced by 73, 257–8 micro-aneurysms 32 midbrain 40 demyelination 104 lesions 10, 78 middle cerebral artery 26 ischaemia... gait 16 heel–knee–shin 16 in multiple sclerosis 104 sensory 80–1 in vestibular disease 81 atenolol 215 atheroma 28 athetosis 74 269 270 atlanto-axial subluxation 93 atrial fibrillation 28 atrial myxoma 28 atypical facial pain 220, 222, 266 aura in epilepsy 197, 198 in migraine 214 auto-antibodies 164 axillary nerve palsy 147 azathioprine in multiple sclerosis 108 in myasthenia gravis 166 baclofen 94 bacterial... intracranial hypertension 49 benign paroxysmal positional vertigo 127, 128, 136, 261 berry aneurysm 32 beta-blockers in benign sex headache 217 in migraine 215 beta-interferon in multiple sclerosis 108 BIH 49 biopsy, brain tumour 51 bitemporal hemianopia 48, 112, 113 blackouts 176–83 bladder function abnormalities 10 in paraplegia 92, 94 blepharospasm 75 body weight in paraplegia 94–5 botulinum toxin therapy... and paraplegia 95 occupational therapy, after stroke 30 oculogyric crisis 75 olfactory nerve 112 ophthalmic artery ischaemia 29 thrombo-embolism 113 optic chiasm 112 compression 113 tumour 47 optic nerve disorders 112–14 in multiple sclerosis 100 , 103 , 113 optic neuritis 103 , 113, 136, 260 oral contraceptives, interaction with anticonvulsant therapy 206, 209 orbital mass lesions 121 osteoarthritis of... unconsciousness contraction myotonia 169 copaxone 108 coprolalia 76 co-proxamol 216 corneal reflex 122 corpus callosum 40, 41, 42 tumour 47 corpus striatum 69, 71, 73 cortical thrombophlebitis 28 corticosteroids in cluster headache 216 in dermatomyositis/ polymyositis 171 in giant cell arteritis 218 in multiple sclerosis 108 in myasthenia gravis 166 myopathy associated with high-dose therapy 171 271 coxsackie viruses . the pres- ence of diabetes, a state of impaired immunity, a previously un- detected site of access or source for infection, a personal contact accounting for the infection, or a visit to a part. the infection is endemic. Such an enquiry is an essential part of the patient’s management. Pyogenic bacterial meningitis Viral meningitis or meningo- encephalitis Tuberculous meningitis Fungal meningitis Cerebral abscess Polymorph count N. clearly aggra- vate the brain lesion. Post-streptococcal syndromes The classic neurological sequel of Group A steptococcal sore throat is subacute chorea, sometimes accompanied by behav- ioural disturbance,